CVE-2021-42839: Grand Vice info Co

This month

HIGH 8.8DOWNGRADE

CVE-2021-42839 is a high-severity flaw (CVSS 8.8) affecting webopac. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Grand Vice info Co. webopac7 file upload function fails to filter special characters. While logging in with general user’s permission, remote attackers can upload malicious script and execute arbitrary code to control the system or interrupt services.

Why this priority

High severity

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	2.4% (top 16%)
CISA exploited list	No
Weakness	CWE-434
Published	2021-11-15
Last modified	2026-06-17

Publisher (CNA): TWCERT/CC · Vendor: vice

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-11-15 10:15 UTCPublished CVE record published
2026-06-17 04:10 UTCUpdated Record last modified

vice webopac DOWNGRADE

Affected: 1.8.20160701 · 7.1.20160701

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.8.20160701

1. Check installed version

apt-cache policy webopac || rpm -q webopac || webopac --version

2. No fixed release: DOWNGRADE to a release before 1.8.20160701 (Debian / Ubuntu)

apt-cache madison webopac sudo apt install webopac=<VERSION_BEFORE_1.8.20160701> sudo apt-mark hold webopac

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list webopac sudo dnf downgrade webopac-<VERSION_BEFORE_1.8.20160701> sudo dnf versionlock add webopac

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-42839?

webopac: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-42839 being exploited?

CVE-2021-42839 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-42839 affect?

CVE-2021-42839 affects webopac. Severity is high (CVSS 8.8). Grand Vice info Co. webopac7 file upload function fails to filter special characters. While logging in with general user’s permission, remote attackers can upload malicious script and execute arbitrary code to control the system or interrup

How urgent is CVE-2021-42839?

Priority 52/100. High severity

Related CVEs

CVE-2021-42838 MEDIUM 6.1 DOWNGRADE Grand Vice info Co

References

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